The use of touch sensors is known in the art for controlling devices through a user interface or man-machine interface. A panel provided with multiple touch sensors distributed under the surface of the panel may constitute a coordinate input surface. That is, the coordinate of the position of a finger, stylus or other object on the surface may be estimated and used as an input to control a device. For instance, electronic apparatuses with touch screens enable users to conveniently select targets, such as web links, with an object such as a finger placed on, i.e. touching, an outer surface above the display.
Touch sensors may for instance work by reacting to the capacitance introduced by a user's finger, or to a change in capacitance caused by the presence of a user's finger.
The detection of touch on a display, or more generally the detection of touch on a coordinate input surface, may also be achieved by other means. One of such means consists in configuring the touch panel such that, if a user touches a particular point of the touch panel, two conductive elements arranged under the outer surface are caused to come into contact with each other so as to be electrically connected. The position on the outer surface that the user has touched may therefore be determined.
For instance, patent application US 2008/0018613 A1 relates to a touch screen display apparatus including such a mechanism for detecting an external pressure. Referring to FIG. 3 and paragraphs [0048] and [0053] of US 2008/0018613 A1 (and using the reference numerals used therein), a first electrode pad 84 is connected to a sensor conductor 24 through a contact hole 71. A second electrode 86 is connected to a data line 62 through a contact hole 73.
When no external pressure is applied on the outer surface (that is, on layer 110 in FIG. 3 of US 2008/0018613 A1), the first electrode pad 84 is not electrically connected to the second electrode 86. In contrast, when external pressure is applied, a sensor electrode 142 comes into contact with both the first electrode pad 84 and the second electrode pad 86. The sensor conductor 24 and the data line 62 are therefore electrically connected together through the sensor electrode 142 at the point where the pressure is applied. Controlling means are provided to detect the electric connection and to recognize the position where the external pressure is applied.
FIGS. 4, 7 and 8 of US 2008/0018613 A1 show some variant configurations of such mechanism.
It is desirable to provide improved sensor assemblies and displays to notably allow finer interactions in the operation of user interfaces. It is also desirable to meet this goal without unduly increasing the complexity and cost of the sensor assemblies and displays.